Μήτσο δες και αυτό...

Σχετικά με εκείνη την κουβέντα που είχαμε κάνει εκείνη την μέρα για το κλίμα δες και αυτό (από wikipedia,http://en.wikipedia.org/wiki/Global_warming)

Solar variation

Solar variation over the last 30 years.
Main article: Solar variation
Hypotheses have been proposed that variations in solar output, possibly amplified by cloud feedbacks, may have contributed to recent warming.[29] A difference between this mechanism and greenhouse warming is that an increase in solar activity should warm the stratosphere while greenhouse warming should cool the stratosphere. Cooling in the lower stratosphere has been observed since at least 1960,[30] which would not be expected if solar activity were the main contributor to recent warming. (Reduction of stratospheric ozone also has a cooling influence but substantial ozone depletion did not occur until the late 1970s.) Phenomena such as solar variation combined with changes in volcanic activity have probably had a warming effect from pre-industrial times to 1950, but a cooling effect since 1950.[1] A related hypothesis is that cosmic rays may affect climate by influencing the generation of cloud condensation nuclei.[31]
A few papers suggest that the Sun's contribution may have been underestimated. Two researchers at Duke University have estimated that the Sun may have contributed about 40–50% of the global surface warming over the period 1900–2000, and about 25–35% between 1980 and 2000.[32] Stott and coauthors suggest that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.[33] Nevertheless, they conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming during the latest decades is attributable to the increases in greenhouse gases.
In 2006, a team of scientists from the United States, Germany, and Switzerland found no net increase of solar brightness over the last thousand years. Solar cycles lead to a small increase of 0.07% in brightness over the last 30 years. This effect is far too minute to contribute significantly to global warming.[34][35] A 2007 paper by Lockwood and Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in cosmic rays.[36]

Φυσικά το wikipedia δεν είναι και ότι πιο αξιόπιστο, αλλά τα ref είναι αξιόλογα